WASHINGTON — The government "shutdown" can teach us a lot about American politics. Even after it's over, a central question will remain. Why did they do it?
Why did congressional Republicans trigger a shutdown for which they would predictably be blamed and from which they could win few Democratic concessions?
The conventional answer blames stupidity, craziness and fanaticism. This is too glib and partisan. It misses a deeper cause that, I believe, helps explain why politics has become more dysfunctional.
By dysfunctional, I mean that it's less able to mediate differences and conflicts. This is, after all, a central purpose of politics.
Broadly speaking, conflicts originate from interest groups and ideologies. The curse of U.S. politics is that it's become less about interests and more about ideologies — and ideologies breed moral absolutes, rigid agendas and strong emotions.
To be sure, interest-group politics can involve huge stakes and fierce disputes: farmers seeking subsidies, multinational companies plugging tax breaks, Social Security recipients protecting benefits.
Sometimes compromises may satisfy everyone, but even when they don't, spillovers are usually modest.
Although adversaries may detest each other, their ill will tends to focus on narrow disagreements.
By contrast, ideological differences are expansive and explosive.
To me, "ideology" extends beyond an explicit political philosophy. It includes broad differences in lifestyles and basic assumptions about America's best interests. In recent decades, ideological issues have occupied more of the political stage for both left and right.
The "size of government" is a proxy for a deep divide.
The left sees bigger government as a tool for social justice; the right fears it's a threat to freedom.
Moral crusades abound. "Saving the planet" (global warming) is one. Preventing "murder" is another; that's gun control for the left and outlawing abortion for the right. The left's campaign for "gay rights" is the right's quest to save the "traditional family."
Just why partisan differences have widened is controversial, but they clearly have.
"Basic beliefs are more polarized along partisan lines than at any point in the past 25 years," said a 2012 Pew opinion study.
One question asked about the need for "stricter laws and regulations to protect the environment."
Among Democrats, 93 percent agreed, the same as in 1992; for Republicans, agreement was 47 percent, down from 86 percent in 1992.